Ovarian cancer is the most lethal of all gynecological cancers and the fourth leading cause of cancer deaths among women. The high mortality rate of ovarian cancer is due to the extraordinarily late presentation of the disease. Fully, 46% of ovarian cancers present when there are already distant metastases and another 26% have advanced regionally. Not surprisingly, therefore, the five-year survival rate for ovarian cancer is low. Any approach which would aid in early diagnosis of this disease could profoundly affect its mortality. A selected panel of cell lines from patients with ovarian cancer is used to identify the molecular genetic differences between benign and malignant cells which may underlie the disease or which may, at the very least, serve as early markers of the disease. Directional cDNA libraries have been constructed from these cell lines. Subtractive cDNA libraries enriched for "malignant-specific" and "benign-specific" cDNAs have been generated.